Assignment of cis-Epoxides and Crystal Structure of cis-4-Nitro-N-(7-oxabicyclo[4.1.0]hept-2-yl)benzamide

The conformations and relative configurations of four epoxides of α-amido cyclohexenes have been determined by the combination of molecular modeling and NMR decoupling technique, cis-Epoxides were deduced from the vicinal coupling constants calculated from the torsional angles H（1）-C（1）-C（2）-H（2） in modeling models by means of Karplus equation and observed by decoupling technique. The crystal structure of cis-4-nitro-N-（7-oxabicyclo[4.1.0]hept-2-yl）benzamide further confirms this assignment.

千屈菜不同部位总黄酮含量及体外抗氧化和降血糖活性

探究千屈菜(Lythrum salicaria L.)根、叶、花3个部位总黄酮含量及体外抗氧化和降血糖活性差异,采用硝酸铝法测定总黄酮含量;通过铁离子还原能力、DPPH(1,1-二苯基-2-三硝基苯肼)和ABTS(2,2′-联苯基-1-氨基-三甲基六碳氢阳离子自由基)自由基清除能力评价体外抗氧化活性;利用α-葡萄糖苷酶和α-淀粉酶的抑制作用评价体外降血糖活性;采用Pearson法分析总黄酮含量与活性的相关性。结果表明,千屈菜花总黄酮含量最高[(36.80±0.10)mg RT/g],清除DPPH自由基能力[IC50为(0.0091±0.0003)mg/mL]、清除ABTS自由基能力[IC50为(0.0744±0.0020)mg/mL]、铁离子还原能力[(2670.78±9.43)μmol VC/g]和对α-葡萄糖苷酶的抑制作用[IC50为(0.567±0.012)mg/mL]最强;千屈菜根对α-淀粉酶的抑制作用[IC50为(0.051±0.003)mg/mL]最强。千屈菜根、叶、花的总黄酮含量与抗氧化活性呈极显著正相关,与降血糖活性呈显著正相关。千屈菜花显示出较强的抗氧化和α-葡萄糖苷酶的抑制作用,根具有较强α-淀粉酶的抑制作用。